Reproducibility and predictive value of a simple novel method to measure atrial fibrillation cycle length in persistent atrial fibrillation – FARS‐AF study

Introduction Different methods are used for atrial fibrillation (AF) cycle length (CL) measurement with variable results. Previous studies of pulmonary vein (PV) CL measurement showed contradictory results on predicting PV isolation (PVI) efficacy. A novel simple method of measuring the average of 10 consecutive Fastest Atrial Repetitive Similar morphology signal (FARS 10 )‐CL to characterize local atrial activity rate was evaluated prospectively. Methods The intra‐observer reproducibility of FARS 10 ‐CL and traditional AF‐CL measurement of continuously fragmented coronary sinus (CS) signals were tested. We prospectively enrolled 100 consecutive patients (62 ± 10 years, 72% male) undergoing wide antral PVI only ablation for persistent AF, measured PV‐FARS 10 ‐CLs, and evaluated long‐term outcome. Results The Kendall area correlation between repeated traditional AF‐CL measurements was −0.006 and between repeated FARS 10 ‐CL measurements in the right and left atrial appendages, CS and PVs were 0.944, 0.859, 0.882, 0.675–0.955, respectively. Patients with recurrent atrial tachyarrhythmia had significantly longer fastest PV‐FARS 10 ‐CL (172 ± 41 vs. 156 ± 41 ms, p = .047). Patients with high burden of spontaneous low‐voltage zone (LVZ) had significantly longer fastest PV‐FARS 10 ‐CL. Freedom from recurrent tachyarrhythmia at 24 months was 85% versus 59% in patients with fastest PV‐FARS 10 ‐CL ≤ 140 versus >140 ms, p = .0018, respectively. In multivariable analysis fastest PV‐FARS 10 ‐CL ≤ 140 ms was the only significant predictor of freedom from recurrent tachyarrhythmia. Conclusions FARS 10 ‐CL measurements have a high reproducibility in contrast to traditional AF‐CL measurement of continuously fragmented CS signals. Patients with high burden of LVZ have longer fastest PV‐FARS 10 ‐CLs. Fastest PV‐FARS 10 ‐CL ≤ 140 ms is associated with a high success of wide antral PVI‐only ablation approach in persistent AF.